1. Field of the Invention
The present invention relates to an apparatus for tracing and cutting a laterally extending anatomical structure in an animal's body including a human body and to methods for making and using same.
More particularly, the present invention relates to an apparatus for tracing and cutting a laterally extending anatomical structure in an animal's body including a human body, where the apparatus includes an elongate flexible body having a proximal end, a distal end, a cutting member extending from the proximal end to the distal end and back through tubes in the flexible body terminating at two opposing apertures in two opposing cutting guides. The apparatus is ideally suited for harvesting tendons or other laterally extending anatomical structures from a surgically accessible point to a desired cutting point along the tendon or other structure within the animal or human body. The present invention also relates to methods for making and using same.
2. Description of the Related Art
The flexor digitorum longus (FDL) and flexor hallucis longus (FHL) tendons are used in a variety of foot reconstructive procedures. These tendons are generally harvested from the midfoot and transferred to a different location in the foot to augment or replace a degenerated tendon.
The FDL is transferred to the navicular bone in treatment of stage II dysfunction of the posterior tibial tendon. The FUL also is used, but less commonly for this purpose. The FHL tendon is more commonly used for Achilles tendon dysfunction caused by chronic tear or degeneration.
With the open operative technique for harvest of the FDL described by Mann and Thompson in J. Bon Joint Surg. 67-A: 556-561, 1985, the FDL sheath is identified at the medial malleolus and followed distally. The abductor hallucis muscle is refracted plantarward to expose the interval between the flexor hallucis brevis and the first metatarsal. The origin of the flexor hallucis brevis muscle is released to increase the exposure of the plantar aspect of the foot. The FDL tendon sheath is opened, and the tendon kept an tension, while the dissection of the sheath is carried distally into the planatar aspect of the foot. As dissection progresses, a number of vessels have to be cauterized. The FDL tendon is sharply divided at the most edistal extent possible. A formal tenodesis of the FEL stump and the FHL distally is not considered necessary because of communicating tendinous slips between the FDL and FHL. This “open” technique requires extensive, deep, and difficult, dissection in the midfoot in the vicinity of blood vessels and nerves.
To improve the success of this technique, the inventor has developed a “minimally invasive” augmented technique. The tendon sheath of the FDL or FHL is identified in the region of the hindfoot through the exposure used for the index procedure, such as exploration of the posterior tibial tendon or the Achilles tendon.
A malleable metallic probe that has a smooth bulb at its tip is introduced within the tendon sheath and passed gently distally into the midfoot where it is easily palpated as shown in FIG. 1A. A vertical incision is then made in the skin of the midfoot over the prominence made by the probe. Once the skin is incised, the central part of the plantar aponeurosis is exposed. The vertically oriented fibers of the aponeurosis are separated to expose muscle fibers of the flexor digitorum brevis muscle. These muscle fibers are then separated and retracted to expose the FDL tendon as shown in FIG. 1B. Because the lateral branch of the medial plantar nerve passes close to the medial border of the flexor digitorum brevis and could be at risk, it is important to make the plantar incision long enough to allow adequate visualization. The identity of the tendon is verified by pulling on the tendon through the proximal incision in the hindfoot and assessing transmission of the tension distally to the tendon in the midfoot and at the same time observing maximal flexion in either the lesser toes or greater toe.
The tendon is then cut sharply in the midfoot and the cut end pulled proximally through the incision in the hindfoot as shown in FIG. 1C.
However, even with the augment technique, the technique involves an additional surgical procedure in a very sensitive area of the foot increasing post operative problems. Thus, there is a need in the art for an apparatus that can be used to harvest tendon and other laterally extending anatomical structures in an animal's body including a human body that does not require additional surgical incisions.